The proposed research is directed to provide some comprehension of the neurochemical mechanisms involved in the behavioral effects of electroshock treatment (EST) by studying the relationships between different EST parameters, resulting EEG seizures, and long-term changes in several neurochemical correlates. Turnover rates of serotonin, and dopamine and electrolytes transport in the cerebrospinal fluid (CSF) will be studied in the intact rabbit brain by a method which combines ventriculocisternal perfusion and isotope dilution techniques. Perfusion experiments will be conducted on the same animal before EST and 1, 7, and 14 days after a series of repeated EST. Release of catecholamines into the perfusate will also be studied. Separate experiments will be conducted to study long-term effects of EST on catecholaminergic, serotonergic and GABA-ergic receptor senstivitiy in several brain areas. In addition, drug interaction with EST will be studied in relation to the EEG seizure and the neurochemical changes: Initial studies will be conducted with Lithium, Imipramine an Carbamezapine.